A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

Giant topiary dog once played a role in a terrorist bomb plot.

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

The world's largest fire hydrant is supposedly tornado-proof.

This psychedelic tromp l'oeil seems to be beckoning drivers to crash into a wall.

The only Bahá'í house of worship in North America and one of only a handful worldwide.

Thanks to an acoustic anomaly, this unassuming stone bench has heard one hundred years of secrets.

The unbelievably opulent home built for an infamous newspaperman.

This Big Sur waterfall drops 80 feet directly into the Pacific Ocean, and inspired the hillside house up top.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."